Lazy eye

What is lazy eye? Lazy eye, or amblyopia, is a condition in which the vision in one eye has not developed properly during early childhood. For one reason or another, the image that this "lazy eye" sends to the brain does not match up to the image sent by the stronger eye. The brain learns to ignore this wrong or blurry image, and over time, the less-developed eye may become weaker, affecting the ongoing development of a child's vision. Without treatment, permanent vision loss can occur. In rare instances, both eyes are considered "lazy," a condition called bilateral amblyopia.

What causes lazy eye? The most common cause of lazy eye is strabismus, or crossed eyes. When a child has strabismus, the eyes cannot line up or look in the same direction at the same time, so one eye "takes over" and the other eye cannot develop good vision. Lazy eye may also happen when the vision in one eye is worse than the other, whether due to nearsightedness, farsightedness, or astigmatism. Cataracts or other problems that may prevent a clear image can also lead to lazy eye.

Who is at risk for lazy eye? About2% to 4% of children under the age of 6 have lazy eye, making it the most common cause of vision problems in children. A child's risk is greater if they also have:

crossed eyes (strabismus)

severe nearsightedness or farsightedness in both eyes

unequal vision in both eyes (e.g., one eye is more nearsighted than the other)

cataract, droopy eyelid, or other factors that could interfere with vision

a family history of lazy eye or crossed eyes

low birth weight or premature birth

What are the signs and symptoms of lazy eye? Well-baby exams and routine childhood eye exams are the best way to detect amblyopia. It is difficult to recognize amblyopia because the stronger eye is able to compensate for the weaker eye. Although in some instances a child's eyes may be visibly misaligned, there are often no outward signs or symptoms of lazy eye. Your child might not realize that one eye's vision is less than the other. Children with lazy eye may squint, tilt their head, close one eye when trying to see, have poor depth perception, or complain of headaches.

What should I do if I think my child has a lazy eye? If you have not had your child's eyes examined, do so as soon as possible. The earlier, the better when it comes to lazy eye: a child's vision continues to develop until around the age of 8 or 9, so early treatment is important to correct lazy eye and ensure a child's vision develops properly.

What happens if lazy eye is not treated? Left untreated, lazy eye can lead to lasting complications. The lazy eye may lose more and more of its vision, leading to permanent vision loss. Depth perception may diminish, since good vision in both eyes is necessary. Injury or disease to the "good" eye could mean a lifetime of poor vision.

How is lazy eye treated? To correct amblyopia,the weaker eye must become stronger so that it can see normally. Depending on the cause of amblyopia, the treatment for lazy eye may include corrective eyeglasses and/or patching of the stronger eye to allow the weaker one to improve. Covering the stronger eye with a patch forces the child to use the weaker one, allowing the child to develop stronger vision in that eye. Prescription eye drops may also be used to blur the vision of the good eye to strengthen the vision in the lazy eye. Surgery may be required to correct cataracts or other problems affecting the eyes.